The dynamically-varying sea ice is blocking efforts to measure the ocean tide on the
circum-Antarctic sea. Recently, the laser altimetry data from the Ice, Cloud, and land
Elevation Satellite (ICESat) provided an opportunity to estimate the freeboard height of
sea ice over the Arctic Ocean and around the Antarctica. The technique of deriving
freeboard statistically detects the leads, which are stretches of open water or thin ice
within fields of sea ice, to determine the along-track sea surface height as the ocean
reference level for the freeboard heights. Based on this method, we estimate the sea
surface height and the freeboard height from ICESat measurements over the circum-
Antarctic sea. We then assess the accuracies of six ocean tide models (GPT99.2, GOT4.7,
TPXO7.1, TPXO7.2, FES04, and CATS2008a) using the crossover difference of sea surface
height.